Method for manufacturing membrane electrode assembly of fuel cell
阅读说明：本技术 燃料电池的膜电极组件的制造方法 (Method for manufacturing membrane electrode assembly of fuel cell ) 是由 松永正文 于 2019-02-19 设计创作，主要内容包括：在薄而敏感的燃料电池用电解质膜上以薄膜涂布包含电解质溶液、担载了催化剂的碳以及水或醇系溶剂或水和醇系溶剂的电极墨、或者核壳型电极墨,制造无变形的膜电极组件。在加热吸附辊的上游设置小直径辊,在所述小直径辊上或离开小直径辊的位置上,使用槽式喷嘴涂布电极墨以形成至少一侧的电极,通过加热吸附辊瞬间蒸发溶剂从而形成电极。(A thin and sensitive electrolyte membrane for a fuel cell is coated with an electrode ink containing an electrolyte solution, catalyst-supporting carbon, and water or an alcohol-based solvent or water and an alcohol-based solvent, or a core-shell type electrode ink, to produce a distortion-free membrane electrode assembly. A small diameter roller is provided upstream of the heating adsorption roller, an electrode ink is applied using a slot nozzle to form an electrode on at least one side on the small diameter roller or at a position apart from the small diameter roller, and a solvent is instantaneously evaporated by heating the adsorption roller to form the electrode.)
1. A method for manufacturing a membrane electrode assembly for a fuel cell, in which a long electrolyte membrane for the fuel cell is continuously or intermittently moved, and an electrode is formed by applying an electrode ink to at least one side of the electrolyte membrane using a slot nozzle, the method comprising:
a step of providing a heating and adsorbing roller for heating and adsorbing the electrolyte membrane coated with the electrode ink;
a step of providing at least one roller having a smaller diameter than the heating suction roller in the vicinity of the heating suction roller upstream of the heating suction roller; and
and applying an electrode ink to a position from the small diameter roller to a position where the electrolyte membrane is in contact with the heating suction roller by using a slot nozzle.
2. The method of manufacturing a membrane electrode assembly for a fuel cell according to claim 1, wherein the heating adsorption roller is a heating roller, and the electrolyte membrane is moved while applying a tension of 20 to 80N to the electrolyte membrane.
3. The method of manufacturing a membrane electrode assembly for a fuel cell according to claim 1, wherein the heated adsorption roller is a heated adsorption belt.
4. The method of manufacturing a membrane electrode assembly for a fuel cell according to any one of claims 1 to 3, wherein the electrolyte membrane before and after the small diameter roller is applied with a tension of 20 to 80N, and the electrode ink is applied to a position before and after the small diameter roller where the electrolyte membrane is separated from the roller.
5. The method of manufacturing a membrane electrode assembly for a fuel cell according to claim 1, wherein the slot nozzle is a gas-assisted slot nozzle or a spray slit nozzle, and a distance between the electrolyte membrane and the nozzle head is set to 0 to 10 mm.
6. The method of manufacturing a membrane electrode assembly for a fuel cell according to claim 1 or 2, wherein the roundness of the heating suction roller or the heating roller is ± 50 μm or less, and the electrode ink is applied to a position where the electrolyte membrane is separated from the roller immediately before the electrolyte membrane comes into contact with the heating suction roller or the heating roller.
7. The method of manufacturing a membrane electrode assembly for a fuel cell according to claim 1 or 5, wherein electrodes of a desired pattern are formed on both sides of the electrolyte membrane, and at least one protective substrate having gas permeability is sandwiched so that the electrodes do not contact each other when the electrodes are wound in such a manner that the electrodes are not attracted on a heating adsorption roller.
8. A method of manufacturing a membrane electrode assembly for a fuel cell, comprising:
applying an anode ink to the electrolyte membrane with a slot nozzle and drying the anode ink, and then, when applying a cathode ink in a particle or fiber form, bringing the reversed electrode surface into contact with an air-permeable base material, sucking the electrolyte membrane on a heating suction roll through the air-permeable base material, and peeling off a back sheet laminated on the electrolyte membrane; and
and forming an electrode containing a catalyst of the cathode on the opposite side of the anode.
Technical Field
The present invention relates generally to a method of coating a long substrate with a liquid film by using a head called a slot die, a slit die, a slot nozzle, or the like. For example, a method of forming an electrode of a Fuel cell, particularly a Fuel cell of the pefc (polymer Electrolyte Membrane cell) type, and an MEA (Membrane electrode assembly) and a Fuel cell manufactured by the method.
The material and shape of the object to be Coated and the material to be Coated are not particularly limited, but the application to a method for forming an electrolyte Membrane or electrode of CCM (Catalyst Coated Membrane) type of MEA is particularly effective in terms of productivity when an electrode is formed by coating an electrode ink on the electrolyte Membrane with a direct slot nozzle.
Background
Conventionally, an electrolyte membrane is mixed with an electrolyte solution, which is one of ionomers, and fine powder made of platinum or the like supported on carbon particles or carbon fibers to form an electrode catalyst ink, and the resulting mixture is applied to a GDL (Gas Diffusion Layer) and pressure-bonded to the electrolyte membrane, or applied to a release film such as PTFE and transferred to the electrolyte membrane. Since the pressure bonding method and the transfer method do not contain a liquid, resistance is generated between the electrolyte membrane and the electrode, and the performance of the fuel cell is degraded. In order to solve this problem, a method of directly applying electrode catalyst ink of CCM system to an electrolyte membrane has been proposed.
Patent document 1 is a method invented by the present inventors, and proposes a method in which an electrolyte membrane for Roll-To-Roll (Roll To Roll) is unwound, and electrode inks are applied in layers by spraying or the like in a state of being adsorbed on a heated adsorption drum or adsorption belt, and dried. Since the electrolyte membrane is laminated in a thin film by spraying or the like in a state of being heated by adsorption by heating of an adsorption drum or the like, the solvent is instantaneously volatilized at the moment when the sprayed particles are applied to the electrolyte membrane and leveled. Therefore, since the adhesion is improved without damaging the electrolyte, the interface resistance between the electrode and the electrolyte membrane can be reduced to the limit, and thus an ideal CCM can be formed. Further, it has also been proposed that a permeable paper having a width wider than that of the electrolyte membrane is provided between the adsorption drum and the electrolyte to attract the electrolyte membrane, and therefore the entire surface of the electrolyte membrane is attracted uniformly without leaving any adsorption traces of the porous body such as the adsorption drum.
Patent document 2 is also a method invented by the present inventors, and proposes a method in which a film as a mask of an electrode shape is bonded To both surfaces of an electrolyte membrane for Roll-To-Roll (Roll To Roll), an electrode-shaped concave portion is formed, and electrode ink is applied and wound while being unwound and adsorbed by a heated adsorption Roll or adsorption tape. In this method, it is recommended to apply the electrode ink while sucking the electrolyte membrane by a heated adsorption drum or the like through the air-permeable base material.
The CCM method is preferable, but since the electrolyte membrane is sensitive to moisture or the like and there are Nafion (r) membranes or the like that deform at a moment when the electrode catalyst ink is applied, it is attempted to apply the electrolyte membrane by a spray nozzle, a slot nozzle or the like while moving the electrolyte membrane without deforming by adsorbing the electrolyte membrane on a heated adsorption belt, a heated adsorption roller or the like as described above. In order to obtain a desired electrode pattern, the spray coating must use a mask, which has difficulty in increasing the production speed.
The slot nozzle is effective for increasing the production speed, but has the following problems when disposed "on roll" on the heated adsorption roll. Since the electrode ink is composed of platinum supported on carbon, an ionomer, water, an alcohol solvent, and the like, when the heating roller is set to about 100 ℃ or higher, condensation occurs at the tip of the groove nozzle which is not heated with the electrolyte membrane interposed therebetween due to a temperature difference due to water and/or solvent vapor of the electrode ink applied, and the applied surface is adversely affected.
In order to prevent this, there is a method of heating the device including the nozzle, but if the temperature of the slot nozzle is high, the nozzle tip is easily dried, and skinning occurs at the nozzle opening, so that the ejection of the electrode ink tends to become unstable.
In addition, even in the case of the suction roll whose roundness is polished to several micrometers or less by the polishing apparatus at room temperature, the roll is largely deformed by deflection due to a complicated structure during heating, and the roundness is extremely poor.
The amount of the electrode catalyst required in recent years is 0.15mg or less per square centimeter at the anode and 0.3mg or less at the cathode, and the specific gravity of the platinum catalyst is 20 or more, so that the film thickness is reduced.
The ratio of platinum to platinum-carrying carbon is also platinum: the carbon is 5: 5, further 7: 3, the dry film thickness containing the ionomer is substantially 1 μm or less and extremely thin, and when the solid content is 10%, the wet film thickness is also 10 μm or less, which is an extremely thin film thickness.
When the heating suction roll is deformed, if the heating suction roll is deformed by a method called a slit nozzle, a slot nozzle, or a slot die which is in contact with the liquid film through the liquid film, the distance between the nozzle tip and the electrolyte film is changed, and a portion having an excessively long distance is generated. In such a case, since the amount of the electrode ink applied is extremely small, the distance between the nozzle tip and the electrolyte membrane is a scale-like porous coating surface due to the thin-film application of the electrode ink, and it is extremely difficult to obtain uniform coating.
In order to solve this problem, japanese patent application laid-open No. 2010-149257 by the present inventors proposes a method of polishing the surface of the suction roller while heating the surface to an application temperature so that the circularity can be 5 μm or less. However, this method requires polishing every time the roll temperature is changed, and thus the workability is extremely poor.
In japanese patent application laid-open publication No. 2015-15258, which is assumed to be at room temperature or after cooling, in which the adsorption roller is polished, a method is proposed in which the roller adsorbing the electrolyte membrane is cooled, the electrode ink is applied to the electrolyte membrane by a slit nozzle, and the electrode ink adsorbed to the electrolyte membrane on the cooling roller is heated by rotating the roller with hot air or infrared rays in the subsequent step.
However, in this method, it is expected that the time from cooling to drying by heating after coating, for example, a Nafion membrane or the like is damaged by solvent impact on the interface of the electrolyte membrane.
Disclosure of Invention
The present invention has been made to solve the above problems, and has been made to rapidly dry the electrode ink applied to the electrolyte membrane without deformation without pursuing the circularity of the heating suction roller. Therefore, the manufacturing cost can be reduced to the limit because the emphasis is not placed on the roundness. On the other hand, since it is common knowledge in the art that the straightness of the tip of the slot nozzle is 5 micrometers or less, and further within 2 micrometers at room temperature by polishing with a polishing apparatus, it is important to use the slot nozzle at room temperature to reduce the influence of heat of the heating suction roller or the heating roller.
Further, by polishing with a polishing apparatus, the roundness at room temperature of a small-diameter roll having a diameter of, for example, 200 mm or less can be suppressed to several micrometers or less. On the other hand, even when heated, a small-diameter roller having a simple internal structure can achieve a roundness of several micrometers or less, and therefore, is used as a pressure-bonding roller for an electrode of a secondary battery.
Therefore, by effectively using these small diameter rollers in combination with the large diameter heating suction roller having a diameter of 200 mm or more or the heating roller having a diameter of 250 mm or more, and providing the groove nozzles on the roller or at a position apart from the roller, it is possible to pattern-coat the electrode ink while maintaining the distance between the electrolyte membrane and the tip of the groove nozzles with high accuracy.
Since the electrolyte membrane is generally manufactured by a casting method, there is a back plate supporting a substrate, and thus coating for forming one electrode can be performed by spray coating or a slot nozzle without deforming the electrolyte membrane. However, since the electrolyte membrane becomes thin and stretches to 25 μm or less, or even 15 μm or less, and there is an extremely sensitive substrate that is easily deformed by moisture in the air as described above, it is extremely difficult to form electrodes on the opposite surfaces, and it is extremely difficult to wind the electrolyte membrane on which the electrodes are formed on both sides of the electrolyte membrane.
The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing a high-quality and durable membrane electrode for PEFC type fuel cells, and to provide CCMs or MEAs in large quantities by high-speed production.
More specifically, an electrode ink is directly applied to an electrolyte membrane of a Roll-to-Roll (Roll to Roll) to produce a high-performance membrane electrode assembly, and a high-performance fuel cell is produced.
The present invention provides a method for manufacturing a membrane electrode assembly for a fuel cell, which is a method for forming an electrode by continuously or intermittently moving a long electrolyte membrane for a fuel cell and applying an electrode ink to at least one side of the electrolyte membrane using a slot nozzle, the method comprising:
a step of providing a heating and adsorbing roller for heating and adsorbing the electrolyte membrane coated with the electrode ink;
a step of providing at least one roller having a smaller diameter than the heating suction roller in the vicinity of the heating suction roller upstream of the heating suction roller; and
and applying an electrode ink to a position from the small diameter roller to a position where the electrolyte membrane is in contact with the heating suction roller by using a slot nozzle.
The invention provides a method for manufacturing a membrane electrode assembly of a fuel cell, which is characterized in that the heating adsorption roller is a heating roller and moves under the condition of applying a tension of 20-80N to the electrolyte membrane.
The invention provides a method for manufacturing a membrane electrode assembly of a fuel cell, which is characterized in that the heating adsorption roller is a heating adsorption belt.
The present invention provides a method for manufacturing a membrane electrode assembly for a fuel cell, wherein a tension of 20-80N is applied to electrolyte membranes before and after a small-diameter roller, and electrode ink is applied to a position where the electrolyte membranes before and after the small-diameter roller are separated from the roller.
The present invention provides a method for manufacturing a membrane electrode assembly for a fuel cell, wherein the slot nozzle is a gas-assisted slot nozzle or a spray slit nozzle, and the distance between an electrolyte membrane and a nozzle head is set to be 0 to 10 mm.
The present invention provides a method for manufacturing a membrane electrode assembly for a fuel cell, wherein the roundness of the heating and adsorbing roller or the heating roller is ± 50 μm or less, and an electrode ink is applied to a position where the electrolyte membrane is separated from the roller immediately before the electrolyte membrane comes into contact with the heating and adsorbing roller or the heating roller.
The present invention provides a method of manufacturing a membrane electrode assembly for a fuel cell, comprising: applying an anode ink to the electrolyte membrane with a slot nozzle and drying the anode ink, and then, when applying a cathode ink in a particle or fiber form, bringing the reversed electrode surface into contact with an air-permeable base material, sucking the electrolyte membrane on a heating suction roll through the air-permeable base material, and peeling off a back sheet laminated on the electrolyte membrane; and forming an electrode containing a catalyst of the cathode on the opposite side of the anode.
The present invention provides a method for manufacturing a membrane electrode assembly for a fuel cell, which is characterized in that an electrode ink is applied on an electrolyte membrane laminated with a back plate and dried to form an electrode, a protective base material with first air permeability is laminated on the electrode, the electrolyte membrane and the electrode are absorbed by a heating absorption drum through the protective base material with the first air permeability, the back plate is peeled off, an electrode ink with the opposite electrode is applied to form an electrode, the air permeable protective base material is recovered, a new second air permeable base material is laminated, and the two electrodes are wound in a state of being protected by the second air permeable base material.
The electrode ink catalyst in the present invention may use a core-shell type catalyst.
According to the method for manufacturing a membrane electrode assembly for a fuel cell of the present invention, even a very thin electrolyte membrane that is sensitive and, for example, 15 μm or less can be directly coated with electrode ink on each surface of the electrolyte membrane. In order to reduce the load on the electrolyte membrane, it is preferable that the electrode ink applied to the electrolyte membrane by heating and suction is capable of volatilizing 99% or more of the amount of the solvent immediately after wetting the electrolyte membrane, for example, within 3 seconds, so that the adhesion between the membrane and the electrode can be improved and the interface resistance can be reduced to the maximum.
In the present invention, the cathode is not limited to the slot nozzle type, and if a spray method or a method of pulse spraying which is a spray method and further adding a velocity to the sprayed particles, that is, an impact pulse method registered by a trademark of MTEK-SMART corporation, is used alone or in combination with the slot nozzle, the adhesion of the catalyst to the electrolyte membrane can be further improved, and an electrode having ideal micropores, mesopores, and macropores can be formed. Further, gas-assisted slot nozzles, spray slot nozzles, melt-blown spray nozzles, or pulse spray may be used.
In the present invention, the number of heads is not limited to a single nozzle head, and a plurality of heads may be arranged in series in the moving direction of the electrolyte membrane to be laminated as a thin film. In particular, by using a gas-assisted slit nozzle, a spray slit nozzle, or a melt-blown nozzle head, the amount of 1 layer of electrode per square centimeter can be adjusted to 0.01 to 0.3mg, and thus, for example, 2 to 30 layers of thin films of electrode ink can be laminated. The amount of coating per layer can be reduced by combining with a heated adsorption drum or the like, but in order to further reduce the amount of coating per layer, for example, the solid content of the electrode ink composed of carbon supported by a platinum catalyst, an electrolyte solution, an alcohol-based solvent, or water and alcohol may be 10% or less, for example, 3% or less in terms of weight ratio.
The solid content concentration is advantageously set to be a thin film as described above, and the load of solvent impact on the electrolyte membrane is reduced as the electrolyte membrane is laminated, and the coating amount per unit area becomes more uniform, thereby improving the performance of the fuel cell.
Further, in the present invention, since the electrolyte membrane can be heated, for example, by heating the adsorption drum at 50 to 120 ℃ via a gas-permeable base material having micropores, for example, a dust-free paper or a gas-permeable plastic film, and sucked by, for example, a commercially available vacuum pump having a vacuum degree of about-60 kPa at low cost, a membrane electrode assembly having no damage to the electrolyte membrane and no defects can be produced. It is economical to use the air permeable substrate wound on a heated adsorption drum. Further, the adhesive is applied in a porous form using gravure rolls or the like on both sides, particularly outside the electrode forming portion of the electrolyte membrane, and the mask base material cut to the electrode size is attached and moved, so that it is possible to form an accurate electrode pattern without using a slot nozzle or a spray method. The mask base material is particularly useful for a spray method for forming electrode ink particles.
The surface of the heating suction roller can be manufactured by forming a plurality of holes with a diameter of 0.1 to 1mm on a cylinder of stainless steel or the like at a pitch of 1 to 3mm, for example, alternately. The plurality of openings may be generally formed by a laser or electron beam. In order to make the adsorption distribution more uniform even in the case of large pores and coarse pores, dust-free paper, a porous film of micron order or the like may be wound around a heated adsorption drum on the surface of the drum and fixed for use. For example, it is economical because it is possible to produce a heating and adsorbing drum at low cost by winding a plurality of layers or preparing a plurality of air-permeable substrates and laminating fine materials in order from the coarse ones. Further, when the micro-or nano-sized air-permeable substrate is used, the effect equivalent to that of the micro-or nano-sized heated adsorption drum is obtained, and therefore, the performance is superior in terms of cost performance. Alternatively, they are not limited to the singular and plural, and may be unwound together with the electrolyte membrane and used in a wound state.
The present invention is capable of manufacturing a membrane electrode assembly having stable quality by directly laminating electrode inks in a thin film state as needed by a slot nozzle, a spray method, or the like on an electrolyte membrane which is not expected to be a very thin film and is easily deformed and difficult to handle when the application of the liquid coating and drying method of jp 2004-351413 is filed.
As described above, according to the present invention, even if the electrode ink is directly applied on the sensitive electrolyte, a desired interface of the membrane electrode can be obtained, and a high-quality membrane electrode assembly and a fuel cell can be manufactured.
Drawings
Fig. 1 is a schematic sectional view showing the arrangement of a heating (adsorption) roller, a small-diameter roller, an electrolyte membrane, and a slot nozzle according to an embodiment of the present invention.
Fig. 2 is a schematic cross-sectional view of a combination of a heating (adsorption) roller, a small-diameter roller, an electrolyte membrane, and a slot nozzle according to an embodiment of the present invention.
Fig. 3 is a schematic sectional view showing the arrangement of a heating (adsorption) roller, an electrolyte membrane, a small-diameter roller, a slot nozzle, and the like, and the moving direction of an air-permeable substrate, and the like, according to the embodiment of the present invention.
Fig. 4 is a schematic cross-sectional view of an inverted electrolyte membrane and other components for forming a second electrode according to the embodiment of the present invention.
Fig. 5 is a schematic cross-sectional view of an electrolyte membrane or the like in a moving direction in application of the second electrode formation according to the embodiment of the present invention.
Fig. 6 is a schematic cross-sectional view of a membrane electrode assembly according to an embodiment of the present invention.
Detailed Description
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The following embodiments are merely examples for facilitating understanding of the present invention, and additions, substitutions, modifications, and the like that can be implemented by those skilled in the art are not excluded within the scope not departing from the technical spirit of the present invention.
The drawings show diagrammatically preferred embodiments of the invention.
In fig. 1, a small diameter roll 4 having a smaller diameter than the heated adsorption drum is provided upstream of the heated adsorption drum 1, and the electrolyte membrane 2 unwound by the unwinding device 5 is applied with an electrode ink, not shown, by the slot nozzle 3 via the drawing roll 10 at a position separated from the roll between the small diameter roll 4 and the heated adsorption drum 1, and the membrane electrode assembly is wound by the winding device 6 downstream. One or more not-shown micron-sized air-permeable substrates can be stacked on the heated suction roll. Electrodes of opposite poles may be formed at the electrolyte membrane. The coating of the electrolyte membrane by the slot nozzle 3 may be performed on the roll of the small diameter roll 4 (on roll), or may be performed before and after the small diameter roll to a position away from the heated adsorption roll (off roll). Ideally, the heating and suction are started almost simultaneously with the coating immediately before the heating and suction roll is moved to a position away from the roll, and therefore, it is also preferable in terms of drying. Particularly, when the process is carried out at a position separated from the roller, the tension of 20-80N is preferably applied to the electrolyte membrane. Since the opening/closing valve mechanism in the groove nozzle can be cleaned by the suck-back method, a rectangular or square electrode pattern can be formed. In addition, in the case where a plurality of patterns are intended to be provided orthogonally to the moving direction, it is convenient to assemble a spacer formed in a desired size.
Fig. 2 is a view in which a plurality of small-diameter rollers (14, 14') are provided in the structure of fig. 1. The slot nozzles 13 may be disposed on the small diameter rolls 14 and 14' or may be disposed at positions separated from the rolls before and after the rolls. In addition, the small diameter roll may also be heated.
Fig. 3 shows an
In fig. 4, the
Fig. 5 is a diagram of forming a second electrode using spray coating instead of a slot jet. The structure is substantially the same as that of fig. 4 except for the spray coating. In addition to the gas-assisted coating method in which the electrode ink is applied together as a mist by an air curtain of the electrode ink flowing out from the spray slit nozzle or the slot nozzle, a mask having substantially the same shape as the first electrode should be provided for the spray coating. The formation of the first electrode is performed at an increased speed of the slot nozzle, and the second electrode can form micro-holes on the electrode corresponding to the cathode by spraying, and thus is effective in terms of performance.
Fig. 6 is a cross-sectional view of the electrolyte membrane 302 having the first electrode 305 and the second electrode 305' formed on both sides thereof, and the protective substrate 348 laminated on the second electrode.
Industrial applicability
According to the present invention, a membrane electrode assembly for a PEFC fuel cell can be manufactured at high speed and high quality.
Description of the reference numerals
1. 11, 31, 41, 51 heating (heat adsorption) drum
2. 12, 32, 42, 302 electrolyte membrane
3. 13, 33, 43 slot type nozzle
4. 14, 14 ', 34', 44 small diameter roller
5. 25, 35, 45, 55 electrolyte membrane unwinding device
6. 26, 36, 46, 56 electrolyte membrane winding device
7、17 CCM
10. 20, 30, 40, 50 pull rolls
38. 138, 148, 248, 348 electrode protection substrates (gas permeable substrates)
39. 49, 59 electrode protection substrate unwinding device
101. 201 electrode protecting substrate winding device
102. 202 backboard winding device
203 spraying coating head
205 electrode
305 first electrode
305' second electrode
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